inter-tenant organizational relationship

Anindya Kumar Banerjee 181 Reputation points
2022-07-19T15:42:34.753+00:00

The following is an excerpt from Organization relationships in Exchange Online
"When you set up the organization relationship, you're responsible for setting up your side of the relationship. You specify the level of information that users in the external organization can view in your organization. The external organization is responsible for setting up their side of the relationship and specifying their level of information that's visible to users in your organization (which might be different than yours)."

However, we encountered a strange outcome when setting up an organization relationship between two tenants today.

There are two Exchange Online tenants abc.com and xyz.com

Users cannot see free busy of one another

First, we set up an organizational relationship in Exchange Online tenant of abc.com and shared free busy with domain xyz.com.

We immediately checked from xyz.com Exchange Online mailboxes if free busy of abc.com Exchange Online mailboxes were visible. Well, they were not. That is the expected behavior. Or is it? Does organizational relationship always require setting up at both tenants? This is my first question.

From abc.com too free busy of xyz.com was not visible, as per expected behavior.

After creating the organizational relationship in abc.com Exchange Online when we checked the details, we found the application Uri and Autodiscover endpoints pointing to on-premises. So, we changed the values to outlook.com and https://autodiscover-s.outlook.com/autodiscover/autodiscover.svc/WSSecurity respectively.

When we checked xyz.com we were still not able to see the free/busy of abc.com.

But wait, when we checked from abc.com we were now able to see free busy of xyz.com.

That is not an expected behavior as per Microsoft documentation, right? Please advise.

PS: abc.com and xyz.com are a single on-prem multi-tenant hybrid.

Microsoft Exchange Online Management
Microsoft Exchange Online Management
Microsoft Exchange Online: A Microsoft email and calendaring hosted service.Management: The act or process of organizing, handling, directing or controlling something.
4,061 questions
Microsoft Exchange Hybrid Management
Microsoft Exchange Hybrid Management
Microsoft Exchange: Microsoft messaging and collaboration software.Hybrid Management: Organizing, handling, directing or controlling hybrid deployments.
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Accepted answer
  1. KyleXu-MSFT 26,201 Reputation points
    2022-07-20T04:08:23.797+00:00

    @Anindya Kumar Banerjee

    We immediately checked from xyz.com Exchange Online mailboxes if free busy of abc.com Exchange Online mailboxes were visible. Well, they were not. That is the expected behavior. Or is it? Does organizational relationship always require setting up at both tenants? This is my first question.

    This phenomenon caused by wrong configuration in "TargetApplicationUri" and "TargetAutodiscoverEpr". After creating relationship between tenant, you need double check value for those two attributes. Then your tenant free/busy will be shared to target tenant.

    PS: abc.com and xyz.com are a single on-prem multi-tenant hybrid.

    If so, I would suggest you try to create a organization relationship with Exchange online default domain name.

    Then check with mailbox which use the default domain name, whether free/busy shared as expected. I guess this phenomenon caused by shared domain name in hybrid.


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  1. Vasil Michev 91,361 Reputation points MVP
    2022-07-19T19:38:39.283+00:00

    When you set up "your end" of the process, you're basically giving the other tenant permissions to see availability info for your users. Thus both sides need to do their part for the process to cover all users.
    With that in mind, when one of the organizations is in Hybrid, you need to set up additional (two-way) relationships, as you effectively have three (or more) organizations now. This is known as the Hybrid mesh and is detailed here: https://techcommunity.microsoft.com/t5/exchange-team-blog/the-hybrid-mesh/ba-p/605910